J. Phys. IV France 112 (2003) 1083
Twin/domain pattern memory in aged Au-49.5Cd martensiteX. Ren1, 2, K. Otsuka3, A. Matsushita1 and M. Nakamura1
1 Materials Physics Group, National Institute for Materials Science, Tsukuba 305-0047, Japan
2 Japan Science and Technology Corporation (JST), Saitama, Japan
3 Nationallnstitute for Materials Science (NIMS), Advanced Materials Laboratory, 1-1 Namiki, Tsukuba 305-0044, Japan
We performed in-situ optical microscopy observations on a Au-49.5Cd single crystal during heatinglcooling and tensile loading/unloading runs. We found that for aged martensite domain pattern can be reproduced or memorized during heating/cooling or stress loading/unloading runs. This mesoscopic memory effect contradicts the basic notion of martensitic transformation that variants/domains are crystallographically and energetically equivalent. It points to the interaction of point defects with martensitic transformation. We show that the interesting mesoscopic memory effect can be fully explained by a general symmetry property of point defects, the symmetry-conforming short-range order property (Ren and Otsuka, Nature, 1997).
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